Common Lab Tests That Are Used in Clinical Practice

On a nearly daily basis, clinicians are using lab tests to assess health, diagnose disease, create treatment plans, and monitor progress and outcomes, which adds up to more than 13 billion lab tests performed each year in the United States. (1) Clinical laboratory tests evaluate samples of blood, urine, or body tissues by assigning a value range to determine if there is an issue that needs to be addressed. (6) 

Utilizing the various common lab tests that are available can be somewhat of an art form and certainly requires targeted expertise when it comes to patient care throughout the patient’s entire lifespan. This is especially true in the case of integrative medicine.

“For medicine at large, the time to intervene is when the labs confirm a pathological condition, but for those of us practicing integrative medicine, we are often looking for dysfunction, which can happen long before an overt disease state,” explains Tina Kaczor, ND, FABNO, who is a naturopathic oncologist and the Editor-in-Chief of the Natural Medicine Journal. She uses fatigue as an example. “A patient may have fatigue, and let’s say pathologies have already been ruled out, but the fatigue remains. A test that looks at organic acids in the urine could inform the clinician of cellular dysfunction, maybe trouble producing energy in the mitochondria. If that is the cause, then correcting this dysfunction can lift the fatigue.”

Some clinical laboratory tests are precise and provide very specific, definitive information, whereas other tests are more general, giving clues that point the practitioner and patient in the right direction. (9) 

Many factors can influence lab test results including:

• Adherence to pre-test instructions
• Age
• Diet
• Ethnicity
• Pharmaceutical medication use
• Sex (6) 

Common lab tests

While there are many lab testing options available to the practitioner, there are common lab tests that are used most frequently. According to the Society for Academic Emergency Medicine, the most commonly ordered tests in hospital emergency departments include: 

• Basic metabolic panel: measures eight different substances in the blood including blood urea nitrogen, calcium, carbon dioxide, chloride, creatinine, glucose, potassium, and sodium
• Cardiopulmonary tests: a specialized type of stress test
• Complete blood count: measures hematocrit, hemoglobin, mean corpuscular volume, platelets, red blood cells, and white blood cells
• Fecal occult blood test: looks for blood in the stool that cannot be seen with the naked eye
• Liver function tests: may include albumin, alkaline phosphatase, alanine transaminase, aspartate aminotransferase, bilirubin, gamma-glutamyl transferase, lactate dehydrogenase, prothrombin time, and total protein
• Magnesium: measures the amount of magnesium in the blood
• Phosphorus: measures the amount of phosphorus in the blood
• Urinalysis: checks the urine for appearance, bacteria, color, crystals, odor, pH, and substances that are not normally in urine (8)

A 2019 analysis of the top clinical laboratory tests performed worldwide by volume and revenue is similar and includes:

• Basic metabolic panel: measures eight different substances in the blood including blood urea nitrogen, calcium, carbon dioxide, chloride, creatinine, glucose, potassium, and sodium
• Blood culture: detects bacteria or fungi in the blood
• Complete blood count: measures hematocrit, hemoglobin, mean corpuscular volume, platelets, red blood cells, and white blood cells
• Glucose: measures the body’s response to sugar
• Lipid panel: detects the amount of cholesterol and other fats in the blood
• Liver function: may include albumin, alkaline phosphatase, alanine transaminase, aspartate aminotransferase, bilirubin, gamma-glutamyl transferase, lactate dehydrogenase, prothrombin time, and total protein
• Pregnancy: to determine if the patient is pregnant
• Thyroid function: to determine if the thyroid gland is functioning properly
• Urinalysis: checks the urine for appearance, bacteria, color, crystals, odor, pH, and substances that are not normally in urine (5) 

In the world of integrative medicine, most practitioners have identified tests that go above and beyond the conventional norm. Based on an interview with integrative medicine pioneer Ronald Hoffman, MD, founder of the Hoffman Center in New York, he often recommends one or more of the following tests to provide even more information to create the most effective treatment plan:

• Ferritin: a sensitive marker of iron status
• Glucose tolerance test (GTT) with insulin: determines how quickly glucose is cleared from the blood and if insulin is too high (metabolic syndrome) or too low (type 1 diabetes)
• Gluten panel: to determine gluten intolerance or celiac disease
• Hemoglobin A1C (HbA1C): provides a record of average blood sugar over 120 days
• High-sensitivity C-reactive protein (hs-CRP): measures a highly-sensitive marker of inflammation and cardiac risk
• Homocysteine: measures the amount of homocysteine in the blood to determine if there is B vitamin deficiency
• LDL particle testing: measures the number and type of LDL particles that impact cardiac risk
• Methylenetetrahydrofolate reductase (MTHFR): looks for MTHFR mutations which may impact how the body processes folate (vitamin B9) (3)
• Omega 3:6 ratio: measures the types of fatty acids in red blood cell membranes reflective of diet and predictive of many degenerative diseases
• Oxidized LDL: looks for heightened free radical activity within the arteries
• Saliva cortisol: measures a sensitive measure of stress and adrenal gland status
• Vitamin B12: measures B12 levels in the blood
• Vitamin D: measures D levels in the blood

“These tests are essential and yet not commonly performed in conventional medicine,” explained Dr. Hoffman.

List of blood tests

The following table outlines a list of values for some of the most common blood tests.

C-reactive protein (CRP) is also measured in the blood and is a critical test because it is an indication of inflammation. In contrast to hs-CRP, which focuses on the circulatory system, CRP is a more general measure of body-wide inflammation. Chronic inflammation has been linked to more than 50% of all deaths worldwide including heart disease, cancer, diabetes, autoimmune, neurodegenerative conditions, and more. (4) CRP is a protein synthesized by the liver that rises in response to inflammation and the higher the level the higher the risk of inflammatory illnesses:

• Normal: <0.3 mg/dL
• Low: 0.3–1 mg/dL
• Moderate: 1–10 mg/dL
• High: 10–50 mg/dL
• Severe: >50 mg/dL (7)

With the variety of tests presently available, it becomes apparent that practitioners have many options when it comes to lab tests.

The bottom line

“Lab tests are one of the many tools we can use to assess someone’s health,” said Dr. Kaczor. “The best use of labs is to compliment the clinical visit either to confirm, rule out, or screen a patient for conditions that are relevant to them.”

Both Dr. Kaczor and Dr. Hoffman say that in some cases, clinical laboratory tests can be expensive for patients, so a prudent, targeted approach is the best way to utilize lab tests.